The move follows complaints from some owners contending their vehicles are not coming close to the advertised 45-47 mpg (5.2-5.0 L/100) city/highway mileage, though a top engineer contends the upgrades are not a reactionary move.

“We’re driven by continuous improvement,” Raj Nair, group vice president-global product development, says. “We’ve dedicated a lot of resources into hybrid technologies and we determined through software we could bring changes into vehicles currently on the market.”

Shortly after the auto maker launched the new Ford C-Max, Fusion and Lincoln MKZ hybrids, customer complaints began to pour in about the less-than-advertised mileage they were achieving. Several took legal action against Ford, and the auto maker still faces a class-action lawsuit about its mileage claims.

Ford responded to the criticism by saying hybrid fuel efficiency varies widely depending on driving style and environmental conditions, and pointed to customers who were able to achieve the 47 mpg bogey.

Software changes include:

Increasing the maximum all-electric speed to 85 mph (137 km/h) from 62 mph (99 km/h), allowing increased use of the electric-only mode on the highway.

Optimizing the use of active grille shutters to reduce aerodynamic drag under more driving and temperature conditions, including cold weather, during air conditioner use and when the engine-coolant temperature is high.

Reducing the electric fan speed as a function of coolant temperature to minimize the fan’s energy consumption.

Shortening engine warm-up time up to 50% to enable electric-only driving and engine shutdown at stops sooner after cold starts.

Optimizing the climate-control system to minimize use of the air-conditioning compressor and reduce the energy used in cold-weather operation.

Nair declines to say how much, if any, improvement in fuel economy customers can expect from the upgrades, noting they won’t affect the hybrids’ Environmental Protection Agency combined rating of 45-47 mpg city/highway, depending on the model.

“Just as individual mileage can vary based on driving styles and environmental conditions, we expect fuel-economy improvements will differ from customer to customer depending on individual driving habits,” he says. “Customers should see the most improvement at highway speeds, during air-conditioner use and operation in colder climates.”

Ford has had discussions with the EPA about changing its test cycle to reflect the greater mileage variability of hybrids, but Nair says no concrete plans have yet been made to alter the procedures.

“We’re open to dialogue with the EPA on revisions they may propose on hybrid testing,” he says. “They’re still working on that.”

Engineers determined some of the new upgrades were possible based on learnings from the auto maker’s plug-in hybrid-electric vehicles, including allowing the hybrids to operate at 85 mph in electric-only mode.

“We have an electric transmission and oil pump that help cool the transmission in electric-only mode,” Nair says. “The transmission and oil temps never get to that (high of a) temperature anyway. So we were able to increase (top EV) speed to the same limit as the PHEVs.”

About 77,000 hybrids on the road today will be eligible for the upgrade, which must be performed at a Ford dealer. Nair says the procedure should take half a day, and vehicles being produced now will come with the upgrades included. He declines to reveal how much this will cost Ford.

The upgrades may not be the last to be offered to owners of both Ford hybrid and conventional vehicles, Nair says, noting the technology embedded in modern vehicles allows for continuous improvements.

“We think these types of upgrades will be happening more often in the future just like upgrades to smartphones and apps,” he says. “If it’s applicable, we will be updating vehicles.”

The controversy surrounding Ford hybrid mileage has not hurt sales, which have been growing.

According to Ford data, its share of the U.S. electrified-vehicle market is up 12 share points to nearly 16% this year, while Toyota’s share has decreased eight points. The auto maker says the No.1 trade-in for the C-Max hybrid is the Toyota Prius.

To spur further growth, Ford says it will expand its electrification engineering jobs by 50% this year and invest $50 million in electrified-vehicle development centers.

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